I am beginning to wonder, though, whether a saturation point will be reached at which people cry, "Enough!" -- a Rubicon that, once crossed, will make people sick to see how much of their personal information is being mined and exploited. If that happens in any serious way, new consumer protections will be demanded -- which, if not granted, might cause millions to opt for the Internet equivalent of going off the grid. So long, Facebook and Twitter.

Ironically, what got me thinking about a privacy backlash was a social networking startup called WayIn, announced earlier this month, that boasts none other than Scott McNealy as its chairman of the board. It's a platform where users "weigh in" by answering quick survey questions generated by other users or by sponsors. WayIn's sweet spot is collecting data while users watch TV and offer opinions in real time -- sports, political debates, commercials, and so on -- and selling it to marketers.

If WayIn takes off, McNealy says sponsors will place high value on the gobs of information users provide. Maybe so. McNealy told me the information delivered to sponsors would be in aggregate, though presumably WayIn would retain accrued responses and more by user account.

By today's standards, that's not particularly intrusive. But is there a limit to this obsessive collection and analysis of user information?

On the analysis side, there's certainly very little limit to the technology that can be applied. Much of the excitement around the Big Data trend centers on mining unstructured data using Hadoop, which Microsoft plans to bring to a wider audience by integrating Hadoop more closely with SQL Server. And what's the unstructured data everyone wants to crunch? Web clickstreams. By analyzing what people do on the Web, sites will be able to improve usability by leaps and bounds -- but they will also get better and better at learning everything about visitors.

I'm not trying to conjure any cheap 1984 paranoia here. After all, InfoWorld and just about every other content business on the Web likes to collect the names of users and ask them to opt into email newsletters, whitepapers, and so on.

The question, ultimately, is whether business should focus so much energy on creating deeper and deeper profiles of users, with unprecedented computing power scouring petabytes of data for interesting patterns to monetize. Over time, as aggressive marketing reveals the scary quantity of information known about users, there may well be a cultural backlash that puts an end to the era where people allow their lives to be an open book. And privacy, that quaint old idea, will come roaring back.